During decarburization procedures the Gas-Cooling Roots Pump vacuum system must operate long time in a tough pressure range. A competent gas-cooling is essential as the extracted warm gases would or else overheat the filter and vacuum system.
With the development of technology and the improvement of item quality in aerospace, energy, iron and steel processing, pharmaceutical and chemical industries, these industries have to obtain a particular vacuum environment. Simultaneously, the vacuum system used by these industries is certainly continuously raising, and the vacuum level is continuously increasing. Moreover, the state’s environmental security, energy saving and three wastes discharge to the above-talked about industries, etc. The requirements are more stringent. At present, the existing dry vacuum pumps out there, such as for example screw vacuum pumps and claw vacuum pumps, cannot meet the requirements of oil-free large pumping acceleration clean vacuum environment proposed by these industries 
because of the restrictions of pumping acceleration characteristics and structural mechanism.
In view of the shortcomings of the prevailing technology, the technical problem to be solved by the utility model is to supply an all-gas-cooled vacuum system to satisfy the use in a clean vacuum environment with huge oil-free pumping speed.